Method for operating a power steering mechanism

• US 20110276230A1
• Filed: 06/08/2011
• Published: 11/10/2011
• Est. Priority Date: 01/13/2009
• Status: Abandoned Application

• Current Assignee: Robert Bosch Automotive Steering GmbH (Robert Bosch GmbH)
• Original Assignee: Robert Bosch Automotive Steering GmbH (Robert Bosch GmbH)
• Inventors: Sprinzl, Michael, Gruener, Stefan, Heilig, Arnulf
• Application Number:
  US13/134,469
• Publication Number:
  US 20110276230A1
• Time in Patent Office: Days
• US Class Current: 701/42
• CPC Class Codes: B62D 5/0484 for reaction to failures, e.g. limp home
• CPC Class Codes: B62D 5/0493 detecting processor errors, e.g. plausibility of steering direction
• CPC Class Codes: B62D 6/008 Control of feed-back to the steering input member, e.g. simulating road feel in steer-by-wire applications

Abstract

A method is disclosed for operating a power steering system in which a motor torque is computed by an electronic processor and established by suitable motor actuation, wherein a plausibility check is carried out for the computed motor torque as part of a 3-level design, wherein integration of a part above a motor torque limit curve and decrementation of an integrator with a part below the motor torque limit curve are performed, the target motor torque being limited to a first integration threshold in level 1, and the limitation is monitored in level 2, with an intrinsically safe motor torque limit curve being used as a function of an actual torque.

Claims

1. A method for operating a power steering system in which comprising computing a motor torque by an electronic processor and established by suitable motor actuation, performing a plausibility check for the computed motor torque as part of a three-level design, wherein integration of a part above a motor torque limit curve and decrementation of an integrator with a part below the motor torque limit curve are performed, the target motor torque being limited to a first integration threshold in level 1 and the limitation being monitored in level 2, and using an intrinsically safe motor torque limit curve as a function of an actual torque.

2. The method according to claim 1, wherein the monitoring limits are broadened under the conditions that the generator operating state of the motor and motor speed are above a certain rotational speed.

3. The method according to claim 1, wherein the power steering system is switched into a safe state when a threshold is exceeded in level 2.

4. A method according to claim 1, wherein the upper or lower limits are broadened only if the direction of rotation is correct.

5. A method according to claim 1, wherein the upper or lower limits are broadened only starting from certain motor torques.

6. A method according to claim 1, wherein the motor torque limit curve is determined by road tests so as to demonstrate the intrinsic safety of the limit curve.

7. A power steering system for a motor vehicle for carrying out a method according to claim 1, comprising:

an electric motor for introducing a predefined additional torque so as to arbitrarily influence steering torque;

a device for acquiring a current manual torque;

a device for acquiring variables for the electric motor;

a device for acquiring a rotor position; and

an electronic control unit for actuating the motor that is adapted to compute a target motor torque so that a desired actuating torque is established at a steering handle,

wherein the control unit is designed to minimize a control deviation between the target and actual actuating torques by computing a target motor torque which can be established by suitable motor actuation.

8. The power steering system according to claim 7, further comprising a microprocessor which communicates with a safety processor.

9. A control unit for use in a power steering system according to claim 7, which is used to actuate an electric motor and is adapted to compute a target motor torque so that a desired actuating torque is established at the steering handle, wherein the control unit is designed to minimize a control deviation between the target and actual actuating torques by computing a target motor torque, which can be established by suitable motor actuation.

10. A computer program comprising program code means for carrying out all the steps of a method according to claim 1, when the computer program is executed on a computer or a corresponding processor.

11. A computer program product comprising program code means, which are stored on a computer-readable data medium, for carrying out all the steps of a method according to claim 1, when the computer program is executed on a computer or a corresponding processor.

12. The method according to claim 2, wherein the power steering system is switched into a safe state when a threshold is exceeded in level 2.

13. A method according to claim 2, wherein the upper or lower limits are broadened only if the direction of rotation is correct.

14. A method according to claim 3, wherein the upper or lower limits are broadened only if the direction of rotation is correct.

15. A method according to claim 2, wherein the upper or lower limits are broadened only starting from certain motor torques.

16. A method according to claim 3, wherein the upper or lower limits are broadened only starting from certain motor torques.

17. A method according to claim 2, wherein the motor torque limit curve is determined by road tests so as to demonstrate the intrinsic safety of the limit curve.

18. A method according to claim 4, wherein the upper or lower limits are broadened only starting from certain motor torques.

19. A power steering system for a motor vehicle comprising:

an electric motor for introducing a predefined additional torque so as to arbitrarily influence steering torque;

a device for acquiring a current manual torque;

a device for acquiring variables for the electric motor;

a device for acquiring a rotor position;

an electronic control unit for actuating the motor that is adapted to compute a target motor torque so that a desired actuating torque is established at a steering handle,

wherein the control unit is operable to minimize a control deviation between the target and actual actuating torques by computing a target motor torque, which can be established by suitable motor actuation.

20. A control unit for use in a power steering system having a steering handle comprising means operable to actuate an electric motor and to compute a target motor torque so that a desired actuating torque is established at the steering handle and a control unit operable to minimize a control deviation between a target and actual actuating torques by computing a target motor torque which can be established by suitable motor actuation.